Potential health effects of dietary nitrate supplementation in aging and chronic degenerative disease

Abstract

In the United States, latest projections indicate the number of adults 65 years of age and older is expected to double by 2050. Given that increased oxidative stress is a hallmark of aging, it is understandable that waning nitric oxide and chronic degenerative disease arise in tandem. To this end, translational evidence-based strategies are needed to mitigate the impending toll on personal and public health. Dietary nitrate supplementation, particularly in the form of beetroot juice, is an active area of inquiry that has gained considerable attention in recent years. Compelling evidence has revealed beetroot juice can elicit potent physiological responses that may offer associated health benefits for multiple clinical disorders including hypertension, dementia, and sarcopenia. Even in the absence of overt disease, age-related impairments in cardiovascular and skeletal muscle function may uniquely benefit from beetroot juice supplementation as evidence has shown blood pressure lowering effects and improved muscle function/contractility - presumably from increased nitric oxide bioavailability. This, in turn, presents a practical opportunity for susceptible populations to support ease of movement and exercise tolerance, both of which may promote free-living physical activity. A theoretical rationale details the potential health effects of dietary nitrate supplementation, wherein a working framework hypothesizes beetroot juice consumption prior to structured exercise training may offer synergistic benefits to aid healthy aging and independent-living among older adults.

Keywords: Arterial stiffness; Beetroot juice; Endothelial dysfunction; Exercise; Nitric oxide.

Conflict of interest statement

Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Copyright © 2020 Elsevier Ltd. All rights reserved.

Figures

Fig. 1.

Schematic illustration highlighting a maladaptive cycle attributed to age-related shifts in physiological function. *Note the attendant consequences of systemic deconditioning often correspond with endothelial dysfunction and arterial stiffening, both of which, adversely affect cardiorespiratory fitness, muscle contractility, and metabolic health.

Fig. 2.

Schematic representation of the oxygen-independent nitrate-nitrite-nitric oxide pathway. Note that commensal facultative anaerobic bacteria convert dietary nitrate to nitrite through the obligatory action of nitrate reductase. Further reduction of nitrite to nitric oxide is hastened in the presence of low oxygen tension and low pH. Nitric oxide elicits many important physiologic functions vital to the defense of acute/chronic disease.

Fig. 3.

Proposed model describing how age-related changes in aerobic fitness and muscle contractility often occur in tandem such that increased fatigue/fatigability would be expected to reduce the likelihood of spontaneous participation in free-living physical activity.